A P I PUBL*1628A 9b = 0732290 0559306 bA9 = Natural Attenuation Processes API PUBLICATION 1628A FIRST EDITION, JULY 1996 Strategies for To, day4 Environmental Partnership American Petroleum Institute[.]
A P I PUBL*1628A 9b = 0732290 0559306 bA9 = `,,-`-`,,`,,`,`,,` - Natural Attenuation Processes API PUBLICATION 1628A FIRST EDITION, JULY 1996 American Petroleum Institute Strategies for To,day4 Environmental Partnership Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ ~ A P I P U B L * A 96 W 0732290 0559107 515 Environmental Partnerrhip One of the most significant long-term trends affecting the future vitality of the petroleum industry is the public’s concerns about the environment Recognizing this trend, API member companies have developed a positive, forward looking strategy called STEP: Strategies for Today’s Environmental Partnership This program aims to address public concerns by improving industry’s environmental, health and safety performance; documenting performance improvements; and communicating them to the public The foundation of STEP is the API Environmental Mission and Guiding Environmental Principles APT standards, by promoting the use of sound engineering and operational practices, are an important means of implementing API’s STEP program The members of the American Petroleum Institute are dedicated to continuous efforts to improve the compatibility of our operations with the environment while economically developing energy resources and supplying high quality products and services to consumers The members recognize the importance of efficiently meeting society’s needs and our responsibility to work with the public, the government, and others to develop and to use natural resources in an environmentally sound manner while protecting the health and safety of our employees and the public To meet these responsibilities, API members pledge to manage our businesses according to these principles: To recognize and to respond to community concerns about our raw materials, products and operations To operate our plants and facilities, and to handle our raw materials and products in a manner that protects the environment, and the safety and health of our employees and the public To make safety, health and environmental considerations a priority in our planning, and our development of new products and processes To advise promptly appropriate officials, employees, customers and the public of information on significant industry-related safety, health and environmental hazards, and to recommend protective measures To counsel customers, transporters and others in the safe use, transportation and disposal of our raw materials, products and waste materiais To economically develop and produce natural resources and to conserve those resources by using energy efficiently To extend knowledge by conducting or supporting research on the safety, health and environmental effects of our raw materials, products, processes and waste materials To commit to reduce overall emissions and waste generation To work with others to resolve problems created by handling and disposal of hazardous substances from our operations To participate with government and others in creating responsible laws, regulations and standards to safeguard the community, workplace and environment To promote these principles and practices by sharing experiences and offering assistance to others who produce, handle, use, transport or dispose of similar raw materials, petroleum products and wastes Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale `,,-`-`,,`,,`,`,,` - API ENVIRONMENTAL MISSION AND GUIDING ENVIRONMENTAL PRINCIPLES ~~ ~ A P I PUBL*Lb28A ~ 2 0559308 451 Natural Attenuation Processes Manufacturing, Distribution and Marketing Department API PUBLICATION 1628A FIRST EDITION, JULY 1996 American Petroleum Institute `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ ~~ A P I PUBL*1628A 96 - 0732290 0559109 398 W SPECIAL NOTES `,,-`-`,,`,,`,`,,` - API publications necessarily address problems of a general nature With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations under local, state, or federal laws Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years Sometimes a one-time extension of up to two years will be added to this review cycle This publication will no longer be in effect five years after its publication date as an operativeAP1 standard or, where an extension has been granted, upon republication Status of the publication can be ascertained from the API Authoring Department [telephone (202) 682-8000] A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C 20005 This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard Questions Concerning the interpretation of the content of this standard or comments and questions concerning the procedures under which this standard was developed should be directed in writing to the director of the Authoring Department (shown on the title page of this document), American Petroleum Institute, 1220 L Street, N.W., Washington, D.C 20005 Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director N I publications may be used by anyone desiring to so Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict API standards are published to facilitate the broad availability of proven, sound engineering and operating practices These standards are not intended to obviate the need for applying sound engineering judgment regarding when and where these standards should be utilized The formulation and publication of MI standards is not intended in any way to inhibit anyone from using any other practices Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard API does not represent, warrant, or guarantee that such products in fact conform to the applicable API standard All rights reserved No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical,photocopying, recording, or otherwise, without prior written permissionfrom the publishex Contact the Publishel; API Publishing Services, 1220 L Street, N W ,Washington, D.C 20005 Copyright O 1996 American Petroleum Institute Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale A P I PUBLxLb28A 0732290 0559LLO DOT FOREWORD `,,-`-`,,`,,`,`,,` - API publications may be used by anyone desiring to so Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict Suggested revisions are invited and should be submitted to the director of the Manufacturing, Distribution and Marketing Department American Petroleum Institute, 1220 L Street, N.W., Washington, D.C 20005 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~~ ~ A P I PUBL*Lb2ôA 96 = 0732290 ~ 0559111 Tqb CONTENTS SECTION 1-INTRODUCTION 1.1 Purpose and Scope 1.2 LNAPL Migration 1.3 Vapor and Dissolved Phase Migration 1 SECTION 2-PHYSICOCHEMICAL PROCESS 2.1 General 2.2 Adsorption and Retardation 2.3 Dispersion 2.4 Diffusion 1 2 SECTION 3-BIOLOGICAL PROCESS 3.1 General 3.2 Aerobic Biodegradation 3.3 Anaerobic Biodegradation SECTION &SUGGESTED PARAMETERS TO BE MONITORED 4.1 General 4.2 Relative Plume Lengths 4.3 Water Quality Changes 4.4 Vadose Zone Air Quality Changes 9 9 6 SECTION - C A S E STUDY 10 15 APPENDIX A-BIBLIOGRAPHY `,,-`-`,,`,,`,`,,` - Figures l-Relationship Between Aqueous Solubility and Octanol-Water Partition Coefficient for Several Groups of Organic Compounds (from Domenico and Schwartz 1990) 2-Relationship Between Longitudinal Dispersivity and Flow Velocity, After Pfannkuch (1962) (from Domenico and Schwartz, 1990) 3-Compilation of Observed RelationshipsBetween Longitudinal Dispersivity and Magnitude of Plume Length, After Gelhar et al., (1985) (from Domenico and Schwartz 1990) &Oxidized Intermediatesof Anaerobic Biodegradation of Selected Aromatic Hydrocarbons (from Cozzarelli et al., 1990) 5-Summary of Results from Laboratory Microbial Evaluation (from Caldwell, et al., 1992) 6-Results of Simulated and Predicted Distribution of BTEX Constituents (from Caldwell, et al., 1992) 7-Results of Predicted Distribution of BTEX With and Without Biodegradation (from Caldwell, et al., 1992) 12 13 14 V Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale ~ API P U B L * L b Z ô A 9b ~ 0732290 0559LL2 982 10 11 `,,-`-`,,`,,`,`,,` - Tables 1-Field-Measured Groundwater and Soil Air Quality Parameters 2-Groundwater Analytical Results vi Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale API PUBL*1628A 9b W 0732290 0559313 819 m Natural Attenuation Processes SECTION 1- INTRODUCTION 1.1 Purpose and Scope range in fluctuation of the LNAPL The LNAPL eventually ceases movement when the lateral and vertical spreading has disseminated it to the extent that the forces driving its movement are overcome by capillary forces in both the vadose and saturated zones These hydrocarbons are then trapped as a residual saturation of LNAPL in these soils and are a source for continued migration in the vapor phase or in the dissolved phase This publication describes the physical, chemical, and biological processes that decrease the concentrations and ultimately limit the extent of the dissolved plume migrating from a hydrocarbon release It is primarily focused on the more soluble hydrocarbon fraction that makes up the dissolved plume Emphasis is given to the biological processes that can play a major role in the attenuation of a dissolved plume 1.3 Vapor and Dissolved Phase Migration 1.2 LNAPL Migration After being released into the subsurface, petroleum hydrocarbons can be affected by the physical, chemical, and biological processes in the immediate vicinity Initially, the hydrocarbons migrate through the vadose zone as a separate light non-aqueous phase liquid (LNAPL), moving downward in response to gravity, and laterally in response to changes in permeabilities encountered This migration continues until (a) the migrating volume is immobilized by capillary forces and held within the pores of the soil in a residual state, (b) the liquid reaches an impermeable layer and perches upon it, or (c) the capillary fringe of the water ,table is encountered where the liquid begins to migrate laterally downgradient When the hydrocarbons reach the capillary fringe, they can migrate laterally because they are lighter, and less dense than water The fluctuations of the water table and capillary fringe cause this LNAPL layer to rise and fall accordingly This coats the soils encountering the LNAPL and, in time, creates a smear zone marking the `,,-`-`,,`,,`,`,,` - Once immobilized, the hydrocarbon compounds can migrate further as vapors or dissolved in water Those compounds that can transfer by volatilization into the air in the vadose zone can eventually migrate as a vapor phase through the land surface and discharge into the atmosphere The compounds in contact with water transfer into the aqueous phase and are transported as a dissolved phase The transfer into the vapor and dissolved phases provides the means for the hydrocarbon compounds to potentially migrate away from the hydrocarbon source area Once released from the source area, the concentrations of the hydrocarbon compounds are decreased by several physical, chemical, and biological processes Given sufficient flow distances and times, these processes can ultimately result in the complete attenuation of the dissolved hydrocarbon compounds These processes are described in this publication SECTION 2-PHYSICOCHEMICAL 2.1 General ( 6CO2 + 3H20 + > 6CO2 + 7H20 + For hexane: C6H14 energy + 9% microorganisms By these reactions the mass requirement of oxygen is 3.1 Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS to 3.5 kilograms per kilogram of hydrocarbon compound, respectively Within the vadose zone, the air in soil pores can contain up to 21 percent oxygen, which is the oxygen concentration in the atmosphere Soils containing petroleum hydrocarbons or naturally high concentrations of organic carbon can have lower oxygen concentrations Aerobic bioactivity is generally considered to become dormant where oxygen concentrations in the soil air are less than percent, conditions that are commonly found within the zone of residual saturation of hydrocarbons Under such conditions, aerobic biodegradation rates become limited to the natural rates of oxygen replenishment This replenishment is largely due to the air exchange caused by barometric pressure and water table fluctuations Oxygen replenished by this air exchange is redistributed within the vadose zone principally by diffusion Within the saturated zone there are important oxygen limitations The oxygen solubility limit for groundwater saturated with air ranges from approximately to 15 m g L and is mg/L at 20'C By these ranges, the dissolved oxygen (DO) in aerated ground water would result in the mineralization of up to 1.7 to 4.8 mg/L of dissolved hydrocarbons Biodegradation is active in the saturated zone in both low DO (e2 mg/L) and high DO (2-8 mgL) conditions However, as oxygen concentrations drop below mgL, there may be a distinct decrease in aerobic bioactivity Chiang et al [i21 found in laboratory studies that microcosms with ground water DO levels ( mg/T., degraded 80 to 100 percent of BTX (120-16,ooO ppb) with t112of 5-20 days When DO levels were and mgk, aromatic hydrocarbon concentrations of 120-1,300 ppb were degraded 20 to 60 percent within 20 to 30 days Studies by Kemblowski et al [13] also showed that biodegradation rates decrease as DO concentrationsdeclined to less than mgk Dissolved oxygen is replenished by hydrodynamic dispersion, diffusion, and reaeration This last process occurs at the capillary fringe interface with the vadose zone Because the petroleum hydrocarbon compounds dissolved in ground water are commonly located in the immediate vicinity of the water table, reaeration is a major source of oxygen Caldwell et al [ 141 found that this reaeration process provided 85 to 90 percent of the oxygen consumed by aerobic biodegradation Anaerobic biodegradation occurs in the absence of or without the use of free using other electron acceptors Because facultative microorganisms can be involved, anaerobic biodegradation usually commences after the oxygen supply has been depleted However, the conditions under which the different anoxic electron acceptors are being used can be overlapping, and several of these anaerobic biodegradation processes can occur simultaneously Not for Resale `,,-`-`,,`,,`,`,,` - API PUBLICATION 1628A ~ A P I P U B L r L b Z B A ỵ b W 2 0559LL9 237 Anaerobic biodegradation rates are distinctly slower than aerobic rates They are usually limited by the reaction rates of the microorganisms involved and the substrate (that is, petroleum hydrocarbon compounds) concentration, rather than the availability of the electron acceptor They are typically not inhibited by high concentrations of petroleum hydrocarbon compounds When nitrate is used as an electron acceptor, it is reduced ultimately to nitrogen gas following the denitrification pathway: NO3 + NO2 + N20 + N2 Using toluene as an example of denitrification-based bioremediation ([lo]): C6HsCH3 + 6NO3 microoroanisms > 7co2 + 4H20 + 3N2 + energy By this reaction, the mass requirement of nitrate is 4.0 kilograms per kilogram of toluene Because nitrate has a higher solubility limit than oxygen, denitrification-based biodegradation can be a potentially important natural process However, the petroleum hydrocarbon compounds biodegraded by the process can be selective and vary among the areas that have been studied For example, Hutchins et al., [ 151 found that benzene was recalcitrant (that is, not biodegraded) under denitrifying conditions, while Major et al [16] found that benzene was degraded Because the investigations of denitrification-based biodegradation in the subsurface have been initiated within the last decade, better characterization of the processes and substrates involved will be forthcoming in the near future Other studies have found iron and manganese reduction to be the electron acceptors involved in the biodegradation of aromatic hydrocarbons [17, 181 Because both are common mineralogical components of the porous media involved, they are a potentially large supply of electron acceptors in anoxic environments They are chiefly found as solids and require microbial species that are able to use them as such While this can result in a buildup of dissolved Fe2+ and Mn2+, the simultaneous generation of sulfide by Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS sulfate reduction can result in the precipitation of Fes from solution; the reduced manganese, however, would not be affected by sulfide buildup [19] Because they can be involved with sulfate reduction, it has been difficult to differentiate direct biodegradation via metals reduction from indirect reduction because of direct microbial reduction of sulfate More information on hydrocarbon biodegradation by iron and manganese reduction will undoubtedly be forthcoming in the near future Sulfate reduction (converting sulfate to sulfide) and methanogenesis (methane production) can be important for biodegradation under strongly reducing conditions This is especially significant where sulfate is a significant constituent in the ambient ground water chemistry or in the subsurface mineralogy The mechanisms for these processes are also poorly understood, but there is empirical evidence accumulating that these processes contribute to the biodegradation of petroleum hydrocarbon compounds For example, Beller et al [20] and Acton and Barker [21] monitored the attenuation of monoaromatic hydrocarbons by sulfate reduction, and Grbi-Cali and Vogel [22] documented biodegradation of aromatic hydrocarbons by methanogenesis Taken together, the anaerobic biodegradation processes can be important in the attenuation of a hydrocarbon plume Cozzarelli et al [25] investigated the anaerobic biodegradation occumng within the dissolved plume migrating from a crude oil spill in northern Minnesota They found reducing, methanogenic conditions prevailing up to 80 meters downgradient of the source area; within ten meters of the source, most of the alkylbenzenes had been degraded to very low concentrations with an accompanying buildup of organic acids Further downgradient these organic acids were also being degraded Benzene and ethylbenzene were the most persistent monoaromatics in the anaerobic zone, with their concentrationsattenuated within a short distance of encountering trace concentrations of dissolved oxygen A number of anaerobic metabolic intermediates of various alkylbenzenes were identified These findings are summarized in Figure Not for Resale `,,-`-`,,`,,`,`,,` - NATURAL ATENUATION PROCESSES 9b A P I PUBL*Zb28A = 0732290 0559320 T59 API PUBLICA~ION 1628A Parent Oxidized intermediates benzene phenol U C H b aCH3 + a benzoic acid toluene &xylene q C H - CH3 etoluic acid CH3 mxylene CH3 mtoluic acid BCH3 + JacooH CH3 pxylene a- CH3 ptoluic acid CHZCH, ? CH3 1-ethyl-2-methylbenzene CHZCH, P CH3 1-ethyl-3-methylbenzene 1-ethyl-4-methylbenzene CH3 CH3 P CH2CooH CH3 mmethylphenylacetic acid - pmethylphenylacetic acid ( k H v COOH) CH3 1.3.5-trimethylbenzene CH3 3.5-dimethylbenzoic acid 1.2.4-trimethylbenzene 2.4-dimethylbenzoicacid & CH3 CH3 1.2.3.5-tetramethylbenzene CH3 2.5-dimethylbenzoic acid 3.4-dimethylbenzoicacid COOH ( “ H q C 0 H ) CH3 2.4.6-tnmethyibenzoicacid C”3 CH3 2.3.5-trimethylbenzoicacid Figure 4 x i d i z e d Intermediatesof Anaerobic Biodegradation of Selected Aromatic Hydrocarbons (from Cozzarelli et al., 1990) `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale A P I PUBL*:1628A 9b = 0732290 0559323 995 = NATURAL ATTENUATION PROCESSES SECTION &SUGGESTED 4.1 PARAMETERS TO BE MONITORED General `,,-`-`,,`,,`,`,,` - There are several parameters that can be monitored to determine the extent to which these physiochemical and biodegradation processes are attenuating the migrating dissolved hydrocarbon compounds The parameters listed in this section are intended to be practical, inexpensive parameters that could be included in typical hydrocarbons investigations 4.2 Relative Plume Lengths A comparison of theoretical and actual plume lengths will give an approximation of attenuation rates For dissolved plumes that have existed for at least several years, the comparison of the downgradient extent of different compounds of the dissolved plume can often reveal significant differences, especially if there are conservative compounds (that is, compounds that move at the same rate as the groundwater, such as chloride) associated with the plume MTBE is considered by some to be a conservative constituent, although that has not been conclusively determined This approach can also be used by comparing the actual extent of a constituent with its theoretical extent based upon its calculated transport rate Parameters for this approach include: a BTEX,or other hydrocarbon chemical(s) of conce b Conservative compound, if any, (for example, CI, MTBE(?)) c Hydraulic conductivity (K) d Hydraulic head gradients e Porosity f Retardation factor Actual plume length and stability can be determined by evaluating time trends in monitoring data The dimensions of the hydrocarbon plume can be plotted for a series of sampiing events, and the relative stability of the plume can be observed Fluctuations in the plume dimensions, if they occur, may also be correlated to changes in site variables such as water levels, infiltration areas, and source removal Several methods can be used to calculate theoretical plume lengths Analytical solutions or numerical modeling can be used to estimate theoretical plume lengths Input parameters are dependent on the method used An expected attenuation rate can be applied to the theoretical solutions to approximate the expected actual plume length Field data points can then be located to calibrate the analytical solu- Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS tion Once the actual steady state plume conditions are determined, a comparison of the two plume lengths will allow for the adjustment of the attenuation rate for the plume 4.3 Water Quality Changes The transfomations in water quality as groundwater flows through the source area can often indicate the presence of anaerobic and/or aerobic biodegradation activity This can best be assessed by collecting groundwater samples upgradient and downgradient of the dissolved plume, within the source area, and in some location(s) within the dissolved plume Groundwater parameters for this approach include: a BTEX,other chemical(s) of concern b Dissolved oxygen (02) c Reduction-oxidation potential (redox) d Chemical oxygen demand (COD) e Biochemical oxygen demand (BOD) f Nitrate (NO3) g Nitrite (NOZ) n Ammonium (NH4+) i Sulfate (SO4) j Methane (CH4) k Iron (Fe2+and Fe3+) Manganese (Mn4+and Mn2+) m Organic acids 4.4 Vadose Zone Air Quality Changes The transformations in the volatile compounds with migration in the vadose zone from the source area can be assessed in two ways A soil gas survey can be conducted in the vicinity of the source area Parameters to be monitored include: a BTEX, total volatile organic compounds, or other chemical(s)of concern b Oxygen (02) c Carbon dioxide C02) d Methane (CH4) Another method that can be used to supplement the soil gas survey is the in situ respiration test This test can be carried out in monitoring wells where oxygen levels are found to be less than two percent The method is best described in the article by Hinchee and Ong [24] Not for Resale A P I P U B L * A 96 = 0732290 0559122 821 = API PUBLICATION 1628A 10 SECTION &CASE To evaluate the effectiveness of the natural attenuation processes in controlling the extent of a dissolved plume of petroleum hydrocarbon compounds, a study was undertaken of several service station sites in southeastern Florida A series of field and laboratory activities was performed to assess the presence of ongoing anaerobic and aerobic biodegradation activity The results for one of the sites are summarized below The study is described more fully by Caldwell et al [14] The study characterized the chemical quality in three zones: (a) upgradient of the hydrocarbons source area, (b) downgradient of the petroleum hydrocarbons source area, and (c) within the source area The ground water and soil air quality in the three zones is summarized in Tables and These results indicated that the upgradient area was aerobic and unaffected by petroleum hydrocarbon compounds Dissolved oxygen was detected, redox potential was strongly oxidizing, and the pH was neutral In contrast, the source area had elevated petroleum hydrocarbon concentrations and was anaerobic The dissolved oxygen was below the method detection limit of 0.2 m a , the redox potential was strongly reducing, and the pH was STUDY depressed by 0.7 units The concentrations of metals and other cations were higher than the upgradient values Downgradient of the source area, petroleum hydrocarbon concentrationswere decreased,but the area was still anaerobic The dissolved oxygen was nondetectable, the redox potential was moderately reducing, and the pH was still slightly depressed These results are consistent with the typical profile through a dissolved plume of petroleum hydrocarbons Laboratory screening of soil samples from each of the three zones was carried out to assess the presence of aerobic microbial populations using plating tests and respirometry tests The results are summarized in Figure The plating tests for all three zones indicated that total heterotrophic populations and microbial populations specifically capable of degrading gasoline were ample, with population densities generally ranging from io5 to io6 colony-forming units per gram dry weight of soil (cfdgdw) The ratios of specific degraders to total heterotrophs were also favorable, ranging from 12 to 36 percent Respirometry tests were also carried out to determine the respiration rate (that is, the rate of oxygen consumption and Table 1-Field-Measured Groundwater and Soil Air Quality Parameters (from Caldwell et al., 1992) Parameter Water10/30/91 Dû (Winkler) Do (ROW Eh PH Conductivity T Soil Vapor DTW ( ) Probe Depth (Probe) Co,(probe) OVA (Robe) Tomethane Upgradient Impacted Zones Downgradient Units MW-7 MW-6 MW-16 mpn mpn mv 2.w2.2 3.2 +279.4 7.25 290 28 NWND 1.35 - 1751-204 6.54 820 30 NDMD 0.75 -46.5 6.66 670 26 NM 7.0 15 NDMD 8.20 7.0 12 ND/ND 7.4 16 ND/ND 7.02 I5 U3 6.02 19.5 95/94 54.3 51.3 (54.9) 26.5 (25.8) 46.5 (45.3) 32 (3 1.2) su mMcm OC ft bls ft bls % % PPm DTW (10/3û91) fi bls 02 (Well) % CO2 (Well) % OVA (Well) PPm TotalMethane Relative Humidity (Well) % (Ambient) T (Well) O C (Ambient) 28.8 DTW= Depth to Water ND = Notdetected NM = Notmeasured `,,-`-`,,`,,`,`,,` - Copyright American Petroleum Institute Provided by IHS under license with API No reproduction or networking permitted without license from IHS Not for Resale NM 7.0 19.5 NDMD A P I PUBL*Lb2öA 96 0732290 5 3 768 11 NATURAL kTrrNUATION PROCESSES Table 2-Groundwater Analytical Results (from Caldwell, et al., 1992) Parameter Dct Limit Units USEPA Impact Upgradient zones Downgradient Method Water < 50 < 50 Benzene Toluene Ethyl Benzene Xylenes Total BïEX lpg& 1Pgn 1Pgn BDL BDL BDL BDL MTBE Pgn BDL 950 320 1270 < 50 TRPH 1m g n BDL 418.1 Toc 1mgn mgn mgn 0.05 m& 16 34 BDL 0.05 BDL 1.8 415.1 405.1 SMWB 353.3 353.3 365.2 350.3 375.4 325.2 CI 5mgn CO2 5- ALK TDS mgn BDL BDL BDL 0.34 BDL BDL BDL 130 140 mgn 160 Ca 50 P g n 47.000 BDL 790 BDL 3,400 BOD COD NO2 NO3 Po4 "4 SO4 Fe Mg Mn Na 0.05 mg/L 0.2 mglL 0.2 m e n 5- 100 P g n 50 Pgn 50 PdL MJ Pgn